Electronic devices are continually shrinking in size to improve portability of the electronic devices. For example, cellular telephones have recently decreased in size to fit in shirt pockets, and are continuing to decrease in size. As the devices shrink, the components inside the device, including the integrated circuits, also shrink. In integrated circuits, a significant amount of the overall thickness is the die rather than circuitry on the die. One method of decreasing the integrated circuit thickness uses thinner dies for the integrated circuits.
Thin dies are fragile and difficult to handle during manufacturing processes. For example, when heating a thin die during reflow, unbalanced stresses in the die cause the die to warp. Warpage results in poor contact between interconnects (e.g., non-wets) leading to yield and reliability problems at die thicknesses less than 100 micrometers. A conventional die attach process having wafer warpage is illustrated in FIGS. 1A-1B.
FIG. 1A is a cross-sectional view illustrating a conventional packaged integrated circuit before heating. A die 120 with interconnects 122 is coupled to a substrate 102 having interconnects 110. The interconnects 122 are attached to the interconnects 110 through a flux material 112. The die 120 and the substrate 102 are heated to reflow the interconnects 122 and the interconnects 110 and bond the interconnects 122 with the interconnects 110.
FIG. 1B is a cross-sectional view illustrating a conventional packaged integrated circuit after heating. During heating, the die 120 may warp due to unbalanced stresses. Warpage at edges of the die 120 is larger than the center of the die 120. As a result, connections 130 are created between the interconnects 122 and the interconnects 110 in the center of the die 120. However, non-wets 132 occur between the interconnects 122 and the interconnects 110 at the edges of the die 120.
The non-wets 132 reduce yield and reliability of integrated circuits manufactured that include the die 120. Thus, there is a need for an improved method of attaching thin dies during manufacturing of integrated circuits.